The present invention relates to a timepiece with a perpetual calender mechanism comprising a date-disc, driving means for said date-disc and means driven at the end of each month by the date-disc, said means acting on said driving means for determining a number of steps of the displacement of said date-disc.
The mechanism makes use of a device of Longines described in the Swiss Pat. No. CH 621 665 and in the Swiss Published Patent Application No. CH 624 533 G. The particular nature of this mechanism is that it permits to effect a rapid changing of the date in both directions of rotation of the hours hand, e.g. when effecting a changing of the indication of time-zones at about midnight.
A mechanism for controlling a semi-perpetual calendar is known from the Swiss Pat. No. CH 574 125. This mechanism comprises a date-disc driving at the end of each month a star-wheel by means of four pins. The star-wheel drives a wheel assembled to a cam which determines the angle of rotation of a lever controlling in its turn the displacement by great or small steps of the date disc. However, the mechanism operates only in the normal direction of rotation of the hands of the timepiece and the setting of the date, the month and the year is difficult.
It is therefore the object of the present invention to provide a timepiece with a perpetual calendar mechanism operating in the two directions of rotation of the hands and in which the corrections of the date, the month and the year are rapid and easy to achieve.